Boeing's 777-300ER, the ultimate stretched
twin, will be heavier, more powerful and able to
fly for longer than its siblings
GUYNORRIS/LOS ANGELES
Boeing's latest 777 derivative, the -300ER, is poised to start a year long flight test and certification effort, with a first delivery to Air France due early next year.
Despite the new paint scheme on the
first 777-300ER, a casual observer could be
forgiven for experiencing a feeling of deja
vu. Apart from some minor details, the new
aircraft is, externally, virtually identical to
the -300 that first flew in October 1997. Yet
beneath the surface, it is a different story -
and the team has its work cut out to test,
verify, demonstrate and certificate this
vastly more capable variant.
Compared to the original -200 model,
the -300ER's maximum take-off weight is
around 90,800kg (200,0001b) greater. It has
a total engine thrust capability of over
230,0001b (l,024kN), roughly equal to the
thrust of three of the 777-200 engines. The
-ER also has a maximum take-off weight
of around 60,0001b more than the -300,
extending its range over the standard
model by 2,410km (l,300nm) to
13,430km, and enabling it to cany an
extra 19,700kg of cargo.
The major difference between the -300ER
and its predecessor is the 115,0001b-thrust
General Electric GE90-115B turbofan,
which is due for US FAR 33 certification
around the time of its first flight. The
engine, the largest turbofan ever developed,
gained exclusivity on the longer-range 777-
200LR/300ER derivatives after a three-way
contest in July 1999. Despite the larger,
3.25m (10.65ft) fan diameter of the -115B,
the engine appears proportionately similar
to its 777-200 predecessors.
Another key development is the pair of
2m-long tapered wingtip extensions,
which increase the span to 64.8m - or
around the same as a 747-400. Made
mostly from composites by Korean Air
Lines' Busan-based Aerospace division, the
new devices are modelled on the tips intro
duced on the 767-400ER and mate to the
wing via wingbox extensions also built by
Korean Air. Boeing expects the tips to gen
erate a 2% fuel efficiency improvement,
producing savings of around 591,000kg in
fuel and $140,000 a year per aircraft.
Modified main gear
Another change requiring closer inspec
tion is the modified semi-levered main
gear that was developed, along with the
aerodynamic and engine changes, to keep
take-off performance within limits at max
imum gross weights.
The main visible difference to the gear is
a large actuator that projects forward from
the main undercarriage post to the front
axle. As the aircraft rotates, the actuator
holds the front part of the truck down,
allowing the aircraft to pivot about the aft
main wheel set. This provides additional
rotation angle, which reduces the required
take-off speed and distance.
All the external changes, and the myriad
modifications to the interior, have been
made to accommodate the much higher
340,195kg gross weight of the longer-range
twins. The aircraft is configured with heav
ier-gauge fuselage and wing skins, revised
and updated systems, and extensive new
interior features such as upper-lobe crew
rests, all of which will form the test pro
gramme's focus. This will consist of several
phases, the first of which has been under
way since October, covering service-ready,
maintenance and system check-out issues.
First flight therefore slots into what is
already a mature test and validation effort.
To date, this has encompassed bench tests
of the second-generation Honeywell air
craft information management system,
Honeywell air supply and cabin pressure
controller, a fifth-generation BAE Systems
electronic engine control, Smiths Aero-
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